At present, it is an important requirement for a user that a connection property to an internet can be maintained during movement. Especially, a state is demanded in which the user can constantly be connected to the internet even when the user moves to any place. When the user moves between networks, an IP address has to be changed, and a problem concerning this address change is solved by introducing a mobile IP.
Moreover, in a working group of mobile nodes and multiple interfaces in IPv6 (Monami6) of Internet Engineering Task Force (IFTF), with regard to mobile nodes of the multiple interfaces, discussion has been advanced in order to supply such a function that characteristics of multiple modes of the nodes can sufficiently be used.
In the mobile nodes of the multiple interfaces, a plurality of care-of addresses acquired in the interfaces can be registered in a home agent. When the plurality of care-of addresses are registered, the home agent can grasp that the mobile nodes can be reached via a plurality of routes.
When this technology is realized, the mobile node can designate a place where the data packet is to be received. It is possible to stipulate a rule in which the care-of address as a destination of a stream (referred to as a flow) of the data packets to be transmitted is designated.
Moreover, in the IETF, in parallel with the above discussion, a discussion has been advanced so as to supply a technique of optimizing a transmission path of the data packet accompanying movement of the mobile node. It is to be noted that this optimization is performed according to various levels and formats. For example, with regard to optimization of end-to-end between a transmitter and a receiver, a basic standard specification of the mobile IP has already been discussed. On the other hand, for example, with regard to the optimization between a mobile router or the mobile node and the home agent, discussion has been advanced in various working groups such as IETF.
Furthermore, in Non-Patent Document 1 described below, a technique (a technology referred to as global HAHA) concerning the optimization performed in the overlay network is proposed. In the technique proposed by Non-Patent Document 1, path optimization which is transparent to an end user is realized using a network of cooperating routers arranged in a geographically scattered manner.
First, the mobile node of the user registers binding information in the home agent. Then, the home agent distributes this binding information to the other home agents arranged in the overlay network in the geographically scattered manner, and resultantly the other home agents can function as proxy home agents of the mobile node.
The data packet received/transmitted with respect to the mobile node is intercepted by the proxy home agent closest to a transmitter node, encapsulated or decapsulated, and then tunneled by another proxy home agent closest to a destination node. In contrast to such a path reaching the destination node from the transmitter node via an original home agent (the home agent in which the binding information is registered by the mobile node), the path of the data packet is optimized between the transmitter node and the destination node.
Moreover, in Patent Document 1 described below, a technology is disclosed in which when the mobile node is not operated, information on the mobile node is not propagated to the other home agent in the overlay network.
Furthermore, in Patent Document 2 described below, a technology is disclosed in which information of the home agents are multi-cast with respect to all controllers and backup devices (backup home agents) to seamlessly switch an operation to the backup home agents in a system constituted of the home agents and the controllers and backup devices of the home agents.
[Patent Document 1] International Patent Application Publication No. WO2006/068439
[Patent Document 2] U.S. Pat. No. 7,080,151
[Non-Patent Document 1] P. Thubert, et al., “Global HA to HA protocol”, Internet Engineering Task Force Internet Draft: draft-thubert-nemo-global-haha-01.txt, Work-In-Progress, 15 Oct. 2005.
However, there are restrictions on a range of the overlay network, and a problem concerning scalability of a technique of Monami6 occurs in, for example, a range and scale in which the overlay network beyond a border of a country and a continent is required.
A capability of a microprocessor is rapidly improving, and it is expected that a user simultaneously plays game, performs voice communication and downloads data so that the mobile node simultaneously communicates with a plurality of communication partners. In this case, each mobile node sets various flow filtering rules concerning processing of flows. However, there is a possibility that each user has a plurality of flow filtering rules. Therefore, when a large number of users are present, very high loads are imposed on memories of the respective network nodes and processing and storage of the rule. Moreover, even in a case where a plurality of paths are distributed to one user terminal in the overlay network, a similar problem concerning the scalability occurs. At present, a technique concerning the optimization of the overlay network is present in this manner, but there is not any solution to a problem in a case where a flow filtering service is supplied in the overlay network.
Furthermore, according to the technology disclosed in Patent Document 1, it is possible to solve, to a certain degree, the problem that as the number of the mobile nodes increases, the loads concerning the flow filtering of the overlay network node rapidly increase, but in actual, a large number of mobile nodes operate and request services. Therefore, in a case where an actual operation is considered, the technology disclosed in Patent Document 1 does not realize a very useful effect.
In addition, the technology disclosed in Patent Document 2 is useful for the operation of the overlay network, but the loads generated owing to an excessive amount of information at each home agent cannot be reduced.